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Abstract:

A method is provided for measuring remaining hydrogen capacity of
hydrogen storage canister incorporating tag information. An information
identification tag is attached to a hydrogen storage canister. The
information identification tag contains therein at least one record of
tag information indicating the hydrogen storage quantity of the hydrogen
storage canister. Once the hydrogen storage quantity is read from the tag
information of the information identification tag and hydrogen
consumption quantity supplied from the hydrogen storage canister is
detected, the hydrogen storage quantity is operated by subtracting the
hydrogen consumption quantity therefrom to calculate a hydrogen residue,
which is then used to update the tag information of the information
identification tag or is stored for subsequent use.

Claims:

1. A method for measuring remaining hydrogen capacity of hydrogen storage
canister by applying tag information, wherein at least one hydrogen
storage canister is provided for supplying hydrogen to support a reaction
in an application device, the hydrogen storage canister comprising an
information identification tag, which stores at least one record of tag
information indicating a hydrogen storage quantity of the hydrogen
storage canister, the method comprising the following steps: (a) reading
the tag information from the information identification tag; (b)
detecting a hydrogen consumption quantity supplied from the hydrogen
storage canister; (c) subtracting the hydrogen consumption quantity from
the hydrogen storage quantity to calculate a residual hydrogen quantity;
and (d) updating the tag information of the information identification
tag by replacing the tag information with the residual hydrogen quantity
so calculated.

2. The method as claimed in claim 1 further comprising, before step (a),
a step of mounting the hydrogen storage canister to the application
device.

3. The method as claimed in claim 1, wherein in step (b), the hydrogen
consumption quantity of the hydrogen storage canister is determined
according to an output current generated by the reaction of the
application device.

4. The method as claimed in claim 1, wherein in step (b), the hydrogen
consumption quantity is determined according to hydrogen flow rate that
is supplied from the hydrogen storage canister to the application device.

5. The method as claimed in claim 1 further comprising, after step (c), a
step of displaying the residual hydrogen quantity and the hydrogen
storage quantity.

6. The method as claimed in claim 1 further comprising, after step (c),
the following steps: (c1) detecting a hydrogen storage pressure of the
hydrogen storage canister; (c2) determining if the hydrogen storage
pressure is lower than a preset hydrogen pressure threshold; and (c3)
determining if the residual hydrogen quantity is lower than a preset
hydrogen residue threshold, when the hydrogen storage pressure is lower
than the hydrogen pressure threshold, for verification of correctness of
the residual hydrogen quantity.

7. The method as claimed in claim 6 further comprising, after step (c3),
a step of issuing an alarm when the residual hydrogen quantity is higher
than the hydrogen residue threshold.

8. The method as claimed in claim 1, wherein the application device
comprises one of a stationary electrical power supply system, a portable
electrical power supply system, and a transportation vehicle.

9. A method for measuring remaining hydrogen capacity of hydrogen storage
canister by applying tag information, wherein at least one hydrogen
storage canister is provided for supplying hydrogen to support a reaction
in an application device, the hydrogen storage canister comprising an
information identification tag, which stores at least one record of tag
information indicating a hydrogen storage quantity of the hydrogen
storage canister, the method comprising the following steps: (a) reading
the tag information from the information identification tag; (b)
detecting a hydrogen consumption quantity supplied from the hydrogen
storage canister; (c) subtracting the hydrogen consumption quantity from
the hydrogen storage quantity to calculate a residual hydrogen quantity;
and (d) storing the residual hydrogen quantity so calculated.

10. The method as claimed in claim 9 further comprising, before step (a),
a step of mounting the hydrogen storage canister to the application
device.

11. The method as claimed in claim 9, wherein in step (b), the hydrogen
consumption quantity of the hydrogen storage canister is determined
according to an output current generated by the reaction of the
application device.

12. The method as claimed in claim 9, wherein in step (b), the hydrogen
consumption quantity is determined according to hydrogen flow rate that
is supplied from the hydrogen storage canister to the application device.

13. The method as claimed in claim 9 further comprising, after step (c),
a step of displaying the residual hydrogen quantity and the hydrogen
storage quantity.

14. The method as claimed in claim 9 further comprising, after step (c),
the following steps: (c1) detecting a hydrogen storage pressure of the
hydrogen storage canister; (c2) determining if the hydrogen storage
pressure is lower than a preset hydrogen pressure threshold; and (c3)
determining if the residual hydrogen quantity is lower than a preset
hydrogen residue threshold, when the hydrogen storage pressure is lower
than the hydrogen pressure threshold, for verification of correctness of
the residual hydrogen quantity.

15. The method as claimed in claim 14 further comprising, after step
(c3), a step of issuing an alarm when the residual hydrogen quantity is
higher than the hydrogen residue threshold.

16. The method as claimed in claim 9, wherein the application device
comprises one of a stationary electrical power supply system, a portable
electrical power supply system, and a transportation vehicle.

Description:

FIELD OF THE INVENTION

[0001] The present invention relates to a method for measuring hydrogen
residue in a hydrogen storage canister, and in particular to a method for
measuring remaining hydrogen capacity of hydrogen storage canister
incorporating RFID device.

BACKGROUND OF THE INVENTION

[0002] Both a hydrogen fuel cell system and an application device powered
by hydrogen fuel cells require a proper supply of hydrogen. Hydrogen
storage is commonly categorized as pressurized hydrogen, liquid hydrogen,
and hydrogen storage alloy, among which pressurized hydrogen is of high
energy, high weight, and high density but is also high in volume and poor
in safety. Liquid hydrogen is also of high energy, high weight, and high
density, but a large consumption of energy is required for liquefaction
of hydrogen, and must be stored in a thermal insulation tank. This makes
the liquid hydrogen fit for storage in a large-sized tank. For general
applications, hydrogen storage alloy is a practical solution, which uses
a canister to serve as a storage container for storage of hydrogen.

SUMMARY OF THE INVENTION

[0003] When hydrogen is supplied from a hydrogen storage canister to for
example a transportation that is powered by a hydrogen storage canister,
a stationary fuel cell power generator operated by a hydrogen storage
canister, or other hydrogen storage canister operated application
devices, it often needs to detect and monitor hydrogen residue remaining
in the hydrogen storage canister before recharging of hydrogen to the
canister or replacing the canister can be made. The state-of-the-art
techniques are advanced enough to allow for fast, convenient and timely
detection of hydrogen residue in a canister. This makes it hard to for
example commercialize and popularize fuel cell systems and application
systems of fuel cell, such as fuel cell powered electrical vehicles.

[0004] Thus, an objective of the present invention is to provide a method
for measuring remaining hydrogen capacity of hydrogen storage canister by
applying tag information, which allows for immediate detection of
hydrogen residue in a hydrogen storage canister for stationary and
portable electrical power supply systems, transportations, and other
application devices, so as to enhance convenience of use and replacement
of hydrogen storage canister in application devices.

[0005] The solution adopted in the present invention to overcome the
problems of the conventional techniques comprises combining an
information identification tag to a hydrogen storage canister, wherein
the information identification tag contains therein at least one record
of RFID device indicating the hydrogen storage quantity of the hydrogen
storage canister. Once the hydrogen storage quantity is read from the tag
information of the information identification tag and hydrogen
consumption quantity supplied from the hydrogen storage canister is
detected, the hydrogen storage quantity is operated by subtracting the
hydrogen consumption quantity therefrom to calculate a hydrogen residue,
which is then used to update the tag information of the information
identification tag or is stored for subsequent use.

[0006] With the technical solution provided by the present invention, the
hydrogen storage quantity of a hydrogen storage canister can be readily
and efficiently retrieved from the information identification tag,
whereby the residual hydrogen quantity remaining in the hydrogen storage
canister can be obtained or calculated and through proper updating of the
tag information contained in the information identification tag or
storing the residual hydrogen quantity so obtained or calculated, it is
possible to identify the current residue of hydrogen remaining in the
canister. This makes it possible to timely identify the current condition
of a hydrogen storage canister for use in various applications, including
for example stationary and portable electrical power supply systems and
transportations.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will be apparent to those skilled in the art
by reading the following description of the best modes for carrying out
the present invention, with reference to the attached drawings, in which:

[0008] FIG. 1 is a system block diagram of the present invention;

[0009]FIG. 2 is circuit block diagram of an information identification
tag used in the present invention;

[0010]FIG. 3 shows a flow chart of a method according to a first
operation mode of the present invention;

[0011]FIG. 4 shows a flow chart of a method according to a second
operation mode of the present invention;

[0012] FIG. 5 is a system block diagram of another embodiment of the
present invention;

[0013]FIG. 6 shows a flow chart of a method according to third operation
mode of the present invention; and

[0014]FIG. 7 shows a flow chart of a method according to a fourth
operation mode of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] With reference to the drawings and in particular to FIGS. 1 and 2,
which are respectively a system block diagram of the present invention
and a circuit block diagram of an information identification tag used in
the present invention, an application device (not shown) comprises a fuel
cell system 100 that comprises a fuel cell stack 1, which generates,
through an electrochemical reaction between hydrogen and air, an
electrical current applied to a load (not shown). The fuel cell stack 1
is combined with a heat exchanger 11 for heat dissipation of the reaction
thereof.

[0016] During the reaction, the fuel cell stack 1 receives a cathode gas
(which in the instant embodiment is air) supplied from an air supply
source 2 and subjected to humidity regulation by a humidifier 21 before
supplied to the fuel cell stack 1. During the reaction, the fuel cell
stack 1 also receives an anode gas (which is the instant embodiment is
hydrogen) supplied from a hydrogen storage canister 3 and conveyed
through a fast connector 31 and a flow regulation valve 32 to the fuel
cell stack 1. Hydrogen is cyclically circulated through the fuel cell
stack 1 by a hydrogen circulator 33.

[0017] The fuel cell system 100 comprises a control circuit, which
comprises a processor unit 41, a display unit 42, a register 43, a memory
unit 44, a current detector 45, a flow meter 46, a pressure sensor 47,
and an alarm unit 48.

[0019] The current detector 45 is connected through an analog-to-digital
converter 451 to the processor unit 41 to detect an output current A
generated by the reaction occurring in the fuel cell stack 1. The flow
meter 46 is connected through an analog-to-digital converter 461 to the
processor unit 41 to detect a hydrogen flow rate F supplied from the
hydrogen storage canister 3 to the fuel cell stack 1. The pressure sensor
47 is connected through an analog-to-digital converter 471 to the
processor unit 41 to detect a hydrogen storage pressure P of the hydrogen
stored in the hydrogen storage canister 3.

[0020] The hydrogen storage canister 3 is provided with an information
identification tag 5, which is a readable and writable tag. In the
instant embodiment, the information identification tag 5 comprises a
radio frequency identification (RFID) tag, which comprises a processing
unit 51, a radio frequency receiver/transmitter module 52, and a memory
unit 53. The memory unit 53 stores therein at least one record of tag
information 531 indicating a hydrogen storage quantity V of the quantity
of hydrogen currently stored in the hydrogen storage canister 3, and
contains other information including serial number (No.), manufacturing
date (D), weight (W), times of being recharged (N) of the hydrogen
storage canister. The tag information 531 of the information
identification tag 5 can be read and written by a tag read/write device 6
serving as a RFID device, which in the instant embodiment comprises an
RFID read/write device.

[0021] Referring to FIG. 3, which shows a flow chart of a method according
to a first operation mode of the present invention, reference being also
made to FIGS. 1 and 2, a hydrogen storage canister 3 that carries an
information identification tag 5 is first mounted to a carriage device C
of an application device (Step 101). Examples of the application device
include devices that powered by hydrogen storage canisters 3, such as
stationary and portable electrical power supply devices (such as fuel
cell power generator) and transportation vehicles (such as electrical
motorcycles and electrical automobiles).

[0022] After the hydrogen storage canister 3 is completely mounted, the
application device is activated (Step 102) to put the fuel cell system
100 of the application device into operation and the hydrogen storage
canister 3 starting supply of hydrogen to the fuel cell stack 1. Then,
the tag read/write device 6 reads the tag information 531 from the memory
unit 53 of the information identification tag 5 (Step 103) to retrieve
the hydrogen storage quantity V of the hydrogen storage canister 3 and
stores the hydrogen storage quantity V to the hydrogen quantity storage
section 441 of the memory unit 44 (Step 104).

[0023] Next, acquirement is made for the hydrogen consumption quantity
ΔV supplied from the hydrogen storage canister 3. Since the
electrical current supplied by the reaction of the fuel cell stack 1 is
substantially proportional to the supply of hydrogen from the hydrogen
storage canister 3, in the instant embodiment, the output current A
generated by the reaction occurring in the fuel cell stack 1 is first
detected by the current detector 45 (Step 105), and the output current A
is then applied through the analog-to-digital converter 451 to the
processor unit 41 to allow the processor unit 41 to make an operation on
the output current A of the fuel cell stack 1 to determine the hydrogen
consumption quantity ΔV of the hydrogen storage canister 3 (Step
106). Afterwards, the processor unit 41 subtracts the hydrogen
consumption quantity ΔV from the hydrogen storage quantity V, which
is previously retrieved, to obtain the residual hydrogen quantity V1 that
currently remains in the hydrogen storage canister 3 (Step 107).

[0024] The residual hydrogen quantity V1 and/or the hydrogen storage
quantity V of the hydrogen storage canister 3 can be displayed or shown
in various ways. In the instant embodiment, a user may determine if to a
residual hydrogen percentage Vr of the hydrogen storage canister 3 (Step
108). In other words, percentage of the residual hydrogen quantity V1 is
calculated to serve as the residual hydrogen percentage Vr (Step 109),
and then the processor unit 41 applies the residual hydrogen percentage
Vr so calculated to the display unit 42 to be displayed thereon (Step
110).

[0025] Once the residual hydrogen quantity V1 is determined, the residual
hydrogen quantity V1 is stored back to the hydrogen quantity storage
section 441 of the memory unit 44 (Step 111). In other words, the
residual hydrogen quantity V1 (which indicates the hydrogen storage
quantity currently remaining in the canister) is used to replace the
hydrogen storage quantity V that was previously retrieved from the
information identification tag 5.

[0026] With the residual hydrogen quantity V1 determined by the operation
of the above steps, the pressure sensor 47 detects the hydrogen storage
pressure P of the hydrogen storage canister 3 (Step 112), which is then
applied through the analog-to-digital converter 471 to the processor unit
41. The processor unit 41 makes a comparison of the hydrogen storage
pressure P with the hydrogen pressure threshold P0 stored in the memory
unit 44 to determine if the hydrogen storage pressure P is lower than the
hydrogen pressure threshold P0 (Step 113).

[0027] The hydrogen storage pressure P of the hydrogen storage canister 3
varies with the decrease of hydrogen contained in the hydrogen storage
canister 3, but generally not in proportion thereto. Thus, it is
generally hard to directly calculate the residual hydrogen quantity V1
from the hydrogen storage pressure P. It is only when the hydrogen
contained in the hydrogen storage canister 3 gets almost exhausted that
the hydrogen storage pressure P becomes clearly lower than the hydrogen
pressure threshold P0, which may thus be feasible for determination of
the run-out of hydrogen of the hydrogen storage canister 3.

[0028] Therefore, when the hydrogen storage pressure P is clearly lower
than the hydrogen pressure threshold P0, it indicates that the canister
almost runs out of hydrogen. Based on such a condition, the processor
unit 41 may correctly determine if the residual hydrogen quantity V1 is
actually lower than the hydrogen residue threshold V0 (Step 114) and
confirmation of correctness of the calculation of the residual hydrogen
quantity V1 can be made. With the confirmation so made, abnormal
situations, such as leakage occurring in the hydrogen storage canister 3,
malfunctioning of control system, and other unexpected failure problems,
can be identified.

[0029] If it is found that the calculated residual hydrogen quantity V1 is
higher than the hydrogen residue threshold V0, then it indicates that the
calculated residual hydrogen quantity V1 does not match the confirmation
made with respect to the result of pressure detection. This may be caused
by leakage of the hydrogen storage canister 3 or malfunctioning of
control system or other unexpected failure problems and under this
condition, the processor unit 41 supplies a control signal S to the alarm
unit 48, making the alarm unit 48 issue an alarm signal to notify the
user (Step 115). In the instant embodiment, the alarm unit 48 comprises a
light alarm, which when actuated, flashes to notify the user.

[0030] In case that the hydrogen storage pressure P is higher than the
hydrogen pressure threshold P0, the processor unit 41 will determine if a
shut-down signal is received (Step 116). If not, re-detection of the
output current A of the fuel cell stack is repeatedly made to timely
determine the consumption of hydrogen of the hydrogen storage canister 3.
In case that a shut-down signal is received, the processor unit 41
transmits the calculated residual hydrogen quantity V1 to the tag
read/write device 6, and the tag read/write device 6 uses the latest
residual hydrogen quantity V1 to update the tag information 531 of the
information identification tag 5 (Step 117) in order to keep the latest
residual hydrogen quantity V1 in the information identification tag 5 for
subsequent use.

[0031] Referring to FIG. 4, which shows a flow chart of a method according
to a second operation mode of the present invention, reference being also
made to FIGS. 1 and 2, a hydrogen storage canister 3 that carries an
information identification tag 5 is first mounted to an application
device (Step 201). The application device is then activated (Step 202) to
put the fuel cell system 100 into operation and the hydrogen storage
canister 3 starting supply of hydrogen to the fuel cell stack 1. Then,
the tag read/write device 6 reads the tag information 531 from the memory
unit 53 of the information identification tag 5 (Step 203) to retrieve
the hydrogen storage quantity V of the hydrogen storage canister 3 and
stores the hydrogen storage quantity to the hydrogen quantity storage
section 441 of the memory unit 44 (Step 204).

[0032] Next, acquirement is made for the hydrogen consumption quantity
ΔV supplied from the hydrogen storage canister 3. In the instant
embodiment, the flow meter 46 is employed to directly detect the hydrogen
flow rate F supplied from the hydrogen storage canister 3 to the fuel
cell stack 1 (Step 205), and the result of detection is transmitted
through the analog-to-digital converter 461 to the processor unit 41 to
allow the processor unit 41 to calculate the hydrogen consumption
quantity ΔV of the hydrogen storage canister 3 from the hydrogen
flow rate F (Step 206). Afterwards, the processor unit 41 subtracts the
hydrogen consumption quantity ΔV from the hydrogen storage quantity
V, which is previously retrieved, to obtain the residual hydrogen
quantity V1 that currently remains in the hydrogen storage canister 3
(Step 207).

[0033] Next, a determination is made whether to display a residual
hydrogen percentage Vr of the hydrogen storage canister 3 (Step 208).
When a user attempts to get aware of the residual hydrogen percentage Vr
of the hydrogen storage canister 3, the processor unit 41 makes an
operation to convert the residual hydrogen quantity V1 into the residual
hydrogen percentage Vr (Step 209), and then transmits the residual
hydrogen percentage Vr to the display unit 42 to be displayed thereon
(Step 210).

[0034] The residual hydrogen quantity V1 so calculated is temporarily held
in the register 43 (Step 211) for speeding up the operation of the
subsequent processes. To verify if the residual hydrogen quantity V1 so
calculated is correct, the pressure sensor 47 detects the hydrogen
storage pressure P of the hydrogen storage canister 3 (Step 212), and the
processor unit 41 compares the detected hydrogen storage pressure P with
the hydrogen pressure threshold P0 contained in the memory unit 44 to
determine if the hydrogen storage pressure P is lower than the hydrogen
pressure threshold P0 (Step 213). When the hydrogen storage pressure P is
lower than the hydrogen pressure threshold P0, a further determination is
made if the residual hydrogen quantity V1 is lower than the hydrogen
residue threshold V0 (Step 214).

[0035] When the residual hydrogen quantity V1 is found higher than the
hydrogen residue threshold V0, it indicates an abnormal situation, such
as leakage of the hydrogen storage canister 3, malfunctioning of control
system, or other unexpected failure problems, occurs. The processor unit
41 then transmits a control signal S to the alarm unit 48, making the
alarm unit 48 issue an alarm signal to notify a user (Step 215).

[0036] In case that the hydrogen storage pressure P is normal, the
processor unit 41 determines if a shut-down signal is received (Step
216). If not, re-detection of the hydrogen flow rate F of the hydrogen
storage canister 3 is repeatedly made. In case that a shut-down signal is
received, the processor unit 41 transmits the calculated residual
hydrogen quantity V1 to the tag read/write device 6, and the tag
read/write device 6 uses the latest residual hydrogen quantity V1 to
update the tag information 531 of the information identification tag 5
(Step 217) in order to keep the latest residual hydrogen quantity V1 in
the information identification tag 5 for subsquent use.

[0037] FIG. 5 shows a system block diagram of another embodiment of the
present invention. This embodiment is substantially identical to the
previous one and identical components/parts/devices are labeled with the
same reference numbers for correspondence. A difference between the
embodiments is that in the instant embodiment, the hydrogen storage
canister 3 of the fuel cell system 100a is provided with an information
identification tag 5a that is readable but not writable.

[0038] The information identification tag 5a adopted in the instant
embodiment is read-only RFID tag, which is readable by a tag read device
6a for retrieval of data. The information identification tag 5a may
alternatively be a set of barcode or a readable/writable tag, provided it
can be read. The tag read device 6a serving as a RFID device may thus be
a barcode reader or an RFID reader that has a single function of reading.

[0039] Referring to FIG. 6, which shows a flow chart of a method according
to third operation mode of the present invention, reference being also
made to FIG. 5, a hydrogen storage canister 3 that carries an information
identification tag 5a is first mounted to an application device (Step
301), and then the application device is activated (Step 302) to put the
fuel cell system 100a into operation and the hydrogen storage canister 3
starting supply of hydrogen to the fuel cell stack 1. Next, it is
determined if the hydrogen storage canister 3 was just replaced (Step
303). If the hydrogen storage canister 3 was not just replaced, a record
that was previously stored in the hydrogen quantity storage section 441
of the memory unit 44 would be retrievable, and the processor unit 41 may
then read from the hydrogen quantity storage section 441 the residual
hydrogen quantity that was previously stored to serve as the current
hydrogen storage quantity V (Step 304).

[0040] If the hydrogen storage canister 3 was just replaced, the processor
unit 41 uses the tag read device 6a to read the tag information of the
information identification tag 5a (Step 305) in order to retrieve the
hydrogen storage quantity V of the hydrogen storage canister 3 and then
stores the hydrogen storage quantity V in the hydrogen quantity storage
section 441 of the memory unit 44 to thereby update the hydrogen quantity
storage section 441 by replacing the original contents thereof with the
hydrogen storage quantity V (Step 306).

[0041] Next, the current detector 45 detects the output current A of the
fuel cell stack 1 (Step 307) for calculation of the hydrogen consumption
quantity ΔV of the hydrogen storage canister 3 from the output
current A (Step 308). The hydrogen storage quantity V is then operated by
subtracting the hydrogen consumption quantity ΔV therefrom to
determine the residual hydrogen quantity V1 (Step 309).

[0042] Next, a determination is made if to display the residual hydrogen
percentage Vr of the hydrogen storage canister 3 (Step 310). If a user
attempts to get aware of the residual hydrogen percentage Vr of the
hydrogen storage canister 3, the processor unit 41 converts the residual
hydrogen quantity V1 into the residual hydrogen percentage Vr (Step 311),
and transmits the residual hydrogen percentage Vr to the display unit 42
to be displayed thereon (Step 312).

[0043] The residual hydrogen quantity V1 so calculated is temporarily held
in the register 43 (Step 313) for speeding up the operation of the
subsequent processes. To verify if the residual hydrogen quantity V1 so
calculated is correct, the pressure sensor 47 detects the hydrogen
storage pressure P of the hydrogen storage canister 3 (Step 314), and the
processor unit 41 compares the detected hydrogen storage pressure P with
the hydrogen pressure threshold P0 contained in the memory unit 44 to
determine if the hydrogen storage pressure P is lower than the hydrogen
pressure threshold P0 (Step 315). When the hydrogen storage pressure P is
lower than the hydrogen pressure threshold P0, a further determination is
made if the residual hydrogen quantity V1 is lower than the hydrogen
residue threshold V0 (Step 316).

[0044] When the residual hydrogen quantity V1 is found higher than the
hydrogen residue threshold V0, it indicates an abnormal situation, such
as leakage of the hydrogen storage canister 3, malfunctioning of control
system, or other unexpected failure problems, occurs. The processor unit
41 then transmits a control signal S to the alarm unit 48, making the
alarm unit 48 issue an alarm signal to notify a user (Step 318).

[0045] In case that the hydrogen storage pressure P is normal, the
processor unit 41 determines if a shut-down signal is received (Step
317). If not, re-detection of the output current A of the fuel cell stack
is repeatedly made. In case that a shut-down signal is received, since in
the instant embodiment, the information identification tag 5a can only be
read, the processor unit 41 instead stores the residual hydrogen quantity
V1 in the hydrogen quantity storage section 441 of the memory unit 44
(Step 319) in order to keep the latest residual hydrogen quantity V1 in
the hydrogen quantity storage section 441 for subsequent use.

[0046] Referring to FIG. 7, which shows a flow chart of a method according
to a fourth operation mode of the present invention, reference being also
made to FIG. 5, a hydrogen storage canister 3 that carries an information
identification tag 5a is first mounted to an application device (Step
401). The application device is then activated (Step 402) to put the fuel
cell system 100a into operation and the hydrogen storage canister 3
starting supply of hydrogen to the fuel cell stack 1. Then, it is
determined if the hydrogen storage canister 3 was just replaced (Step
403). If the hydrogen storage canister 3 was not just replaced, a record
that was previously stored in the hydrogen quantity storage section 441
of the memory unit 44 would be retrievable, and the processor unit 41 may
then read from the hydrogen quantity storage section 441 the residual
hydrogen quantity that was previously stored to serve as the current
hydrogen storage quantity V (Step 404).

[0047] If the hydrogen storage canister 3 was just replaced, the processor
unit 41 uses the tag read device 6a to read the tag information of the
information identification tag 5a (Step 405) in order to retrieve the
hydrogen storage quantity V of the hydrogen storage canister 3 and then
stores the hydrogen storage quantity V in the hydrogen quantity storage
section 441 of the memory unit 44 to thereby update the hydrogen quantity
storage section 441 by replacing the original contents thereof with the
hydrogen storage quantity (Step 406).

[0049] Next, a determination is made if to display the residual hydrogen
percentage Vr of the hydrogen storage canister 3 (Step 410). If a user
attempts to get aware of the residual hydrogen percentage Vr of the
hydrogen storage canister 3, the processor unit 41 converts the residual
hydrogen quantity V1 into the residual hydrogen percentage Vr (Step 411),
and transmits the residual hydrogen percentage Vr to the display unit 42
to be displayed thereon (Step 412).

[0050] The residual hydrogen quantity V1 so calculated is temporarily held
in the register 43 (Step 413) for speeding up the operation of the
subsequent processes. To verify if the residual hydrogen quantity V1 so
calculated is correct, the pressure sensor 47 detects the hydrogen
storage pressure P of the hydrogen storage canister 3 (Step 414), and the
processor unit 41 compares the detected hydrogen storage pressure P with
the hydrogen pressure threshold P0 contained in the memory unit 44 to
determine if the hydrogen storage pressure P is lower than the hydrogen
pressure threshold P0 (Step 415). When the hydrogen storage pressure P is
lower than the hydrogen pressure threshold P0, a further determination is
made if the residual hydrogen quantity V1 is lower than the hydrogen
residue threshold V0 (Step 416).

[0051] When the residual hydrogen quantity V1 is found higher than the
hydrogen residue threshold V0, it indicates an abnormal situation, such
as leakage of the hydrogen storage canister 3, malfunctioning of control
system, or other unexpected failure problems, occurs. The processor unit
41 then transmits a control signal S to the alarm unit 48, making the
alarm unit 48 issue an alarm signal to notify a user (Step 418).

[0052] In case that the hydrogen storage pressure P is normal, the
processor unit 41 determines if a shut-down signal is received (Step
417). If not, re-detection of the hydrogen flow rate F of the hydrogen
storage canister 3 is repeatedly made. In case that a shut-down signal is
received, the residual hydrogen quantity V1 is stored in the hydrogen
quantity storage section 441 of the memory unit 44 (Step 419) in order to
keep the latest residual hydrogen quantity V1 in the hydrogen quantity
storage section 441 for subsequent use.

[0053] Although the present invention has been described with reference to
the best modes for carrying out the present invention, it is apparent to
those skilled in the art that a variety of modifications and changes may
be made without departing from the scope of the present invention which
is intended to be defined by the appended claims.